Here's their statement to WaPo:
As a result of media reports that BellSouth provided massive amounts of customer calling information under a contract with the NSA, the company conducted an internal review to determine the facts. Based on our review to date, we have confirmed no such contract exists and we have not provided bulk customer calling records to the NSA.05/16/2006, 10:00 a.m. Update: According to a CBS/AP report, USA Today has pushed a BellSouth spokeman to define "bulk customer calling records":
When USA Today asked BellSouth to define "bulk customer calling records," BellSouth spokesman Jeff Battcher said: "We are not providing any information to the NSA, period." He said he did not know whether BellSouth had a contract with the Department of Defense, which oversees the NSA, USA Today reports.